I have a 2003 GMC sonoma with a 4.3L Vortec V-6. I just purchased the truck and are having some rough idling problems. Forums suggest cleaning the EGR valve. I cannot figure out where it is. Can someone help me out with this? Maybe a pic?

The mid-02 and up do not have an EGR valve. GM redesigned the 4.3L and introduced it in the middle of the 2002 production run. The fuel injection spider, EGR system, knock sensor type, and a few other "refinements" were made at that time.Have a scan tool capable of opening and closing the related solenoids in the EVAP system to verify that they were working? Did you check the engine for smoke in the intake that would result from a malfunctioning EVAP purge solenoid? If the purge solenoid were stuck open, then it could act similar to a failed or failing EGR valve.Have a shop with a dyno, do a Drive cycle to refine the problem. Here is a link on what a drive Cycle is.http://www.obdii.com/drivecycle.htmlGood luck and hope this helps. You can always go to Auto Zone and have them scan the truck for any codes, it just may time for a tune up. Not know how the truck has been taken care of before you, try add Marvel Mystery Oil to the engine 1000 miles before it's oil change. That should clean up any internal dirt and do not use any engine oil flush, that just promotes oil leak.Keep me posted on how things are going, I also found that the only thing the GM 4.3 like is the OEM distributor cap and rotor, every after market gave me a rough running engine.

I don't have a pic but can tell you that its connected to both the air intake and the exhaust system could be electrically operated or vacum but i would be expecting it to be staling if this was open a little

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It may just be a dirty MAF sensor, you may want to spray carb cleaner into the intake to clean out. Check also the idle air control valve. IT may also just be dirty. Check for loose vacuum hose. If you can, have a scanner connected to the diagnostic port to see if there are errors. Some shops would let you borrow their scanners.